$4)$ Mr$.$ Beautiful, an organization that sells weight training sets, has an ordering cost of $ $40$ for the BB$-1$ set. $($BB$-1$ stands for Body Beautiful Number $1.)$ The carrying cost for BB$-1$ is $ $5$ per set per year. To meet demand, Mr$.$ Beautiful orders large quantities of B B$-1$ 'seven times a year. The stockout cost for BB$-1$ is estimated to be $ $50$ per set. Over the past several years, Mr$.$ Beautiful has observed the following demand during the lead time for BB$-1$ : The reorder point for BB$-1$ is $60$ sets. What level of safety stock should be maintained for BB$1?$